Calibration block



FIG. 1 is a left side elevation view of the calibration block;

FIG. 2 is a right side elevation view thereof;

FIG. 3 is a front elevation view thereof;

FIG. 4 is a rear elevation view thereof;

FIG. 5 is a top plan view thereof;

FIG. 6 is a bottom plan view thereof;

FIG. 7 is a front perspective view thereof; and,

FIG. 8 is a side perspective view thereof. 

CLAIM I claim the ornamental design for a calibration block, as shown and described. 